4/27/2008

Breaking Earth NewsNevada, USAImage: A man who said his name was Juan cleans up the groceries that toppled from the shelves at Save Mart in Northwest Reno after Friday night's strong earthquake April 25, 2008. The quake had a preliminary reading of 4.7 and is the latest of 100's of earthquakes that have swarmed the northwest Reno area in the past six weeks with the quakes getting progressively stronger. (AP Photo/Reno Gazette Journal - Marilyn Newton)Story: Scientists urged residents of northern Nevada's largest city, Reno, to prepare for a bigger event as the area continued rumbling Saturday after THE LARGEST EARTHQUAKE IN A TWO-MONTH-LONG SERIES of temblors. More than 100 aftershocks were recorded on the western edge of the city after a magnitude 4.7 quake hit Friday night, the strongest quake around Reno since one measuring 5.2 in 1953. The latest quake swept store shelves clean, cracked walls in homes and dislodged rocks on hillsides, but there were no reports of injuries or widespread major damage. Seismologists said the recent activity is UNUSUAL because the quakes started out small and continue to build in strength. The normal pattern is for a main quake followed by smaller aftershocks. "A magnitude 6 quake wouldn't be a scientific surprise. We certainly hope residents are taking the threat seriously after last night." Reno's last major quake measured 6.1 on April 24, 1914, and was felt as far away as Berkeley, California. A rockslide triggered by Friday night's quake was blamed for causing a 125-foot breach in a wooden flume that carries water to one of two water treatment plants in Reno, a city of about 210,000. A backup pump was used to divert water to the plant, and the breach was not expected to cause any water shortages. Friday night's quake was centered around Mogul, just west of Reno. The area of upscale homes along the eastern Sierra was rattled by more than 100 quakes the day before, the strongest a magnitude 4.2 that caused high-rise casinos to sway in downtown Reno. The strongest aftershock measured 3.7 and was recorded early Saturday. Hundreds of mostly minor quakes have occurred along one or possibly more faults since the sequence began Feb. 28. The quakes have occurred along an area about 2 miles long and a half-mile wide. "We can't put a number on it, but the probability of a major earthquake has increased with this sequence." It's getting a little bit frightening. I'm very concerned about this increase in not only activity, but also in magnitude." The quakes around Reno began a week after a magnitude 6 temblor in the northern Nevada town of Wells, near the Utah border. The Feb. 21 quake caused an estimated $778,000 in damage to homes, schools and historic downtown buildings. Scientists said they're unsure whether the seismic activity at opposite sides of Nevada is related.